In a network deployment scenario, there are two types of network nodes, which are a E-UTRAN NodeB (eNB) and a small cell node (SCN). The eNB and the SCN each control one or more cells. A frequency used by a cell served by the eNB may be different from a frequency used by a cell of the SCN. The cell of the eNB uses a frequency F1, and the cell of the SCN uses a frequency F2. The eNB has large cell coverage, and may be referred to as a macro access network node. The SCN has small cell coverage, and may be referred to as a small access network node. Within coverage of a macro access network node or in the vicinity of the macro access network node, there may be multiple small access network nodes. Small access network nodes are generally deployed in service hotspot areas to help a macro access network node to offload services in those areas.
According to a quantity of deployed small access network nodes, deployment scenarios may be classified into two types: sparse deployment and dense deployment. In a sparse deployment scenario, the quantity of small access network nodes is small, and only one or several SCNs may be deployed in one service hotspot area. In a dense deployment scenario, the quantity of small access network nodes is large, and a large quantity of SCNs may be deployed in one service hotspot area.
In addition, service hotspot areas are generally discontinuous; therefore, generally coverage of small access network nodes is also discontinuous. One service hotspot area is covered by a cluster of small access network nodes. Small access network nodes in a same cluster are generally neighboring to each other, while different clusters of small access network nodes are probably not neighboring to each other.
Referring to FIG. 1, in an existing network architecture, an SCN is connected to an eNB through an X interface, and there is no direct interface between the SCN and core network nodes. The core network nodes herein include a mobility management entity (Mobility Management Entity, MME) and a serving gateway (Serving GateWay, SGW). The X interface may be a new interface, an existing S1 or X2 interface, or the like. The eNB is connected to the MME through an S1-c interface, and connected to the SGW through an S1-u interface. The MME is connected to the SGW through an S11 interface.
In the prior art, the eNB is responsible for forwarding to the SCN downlink user data sent by the SGW, and responsible for forwarding to the SGW uplink user data sent by the SCN. In a sparse deployment scenario, the quantity of SCNs deployed within coverage of one eNB is limited, and the architecture may work properly. However, as the quantity of SCNs deployed in a network increases, the sparse deployment scenario may gradually evolve into a dense deployment scenario. In the dense deployment scenario, the quantity of SCNs deployed within coverage of one eNB may be large, and consequently, the following problems are caused to the existing architecture.
1. As the quantity of SCNs increases, data to be forwarded by the eNB increases, and finally, the eNB may be unable to work properly due to too heavy load.
2. As the quantity of SCNs increases, data transmitted over a connection between the eNB and the SGW also increases, and finally, congestion occurs on the connection.